Recupeare la connessione nella configurazione in Asp net core

[fermat]

ciao!

mi sto intriducendo ad Asp net core mvc, e vorrei recuperare la connessione creata nel file di configurazione appsettings.json:

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "ZaraConn": "Server=IP_ADDRESS;Database=NOME_DB;user id=USER;password=PWD;Trusted_Connection=True;MultipleActiveResultSets=true"
  }
}

nel controller, giusto per capire se funziona o meno:

using System;
using System.Diagnostics;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using CSharpNetCoreWeb.Models;
using Microsoft.Extensions.Configuration;
using System.Data.SqlClient;

namespace CSharpNetCoreWeb.Controllers
{
    public class HomeController : Controller
    {
        private readonly ILogger<HomeController> _logger;
        public IConfiguration Configuration { get; }

        public HomeController(ILogger<HomeController> logger)
        {
            _logger = logger;
            string connectionString = Configuration["ConnectionStrings:ZaraConn"];
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                string sql = "SELECT * FROM Richieste";
                SqlCommand command = new SqlCommand(sql, connection);
                using (SqlDataReader dataReader = command.ExecuteReader())
                {
                    while (dataReader.Read())
                    {
                        Console.WriteLine(dataReader[0]);
                    }
                }
                connection.Close();
            }
        }

        public IActionResult Index()
        {
            return View();
        }

        public IActionResult Privacy()
        {
            return View();
        }

        [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
        public IActionResult Error()
        {
            return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
        }
    }
}

ma ottengo questo errore:

System.NullReferenceException: 'Object reference not set to an instance of an object.'

CSharpNetCoreWeb.Controllers.HomeController.Configuration.get ha restituito null.

qualche suggerimento??